1、;i I 3 -i : I TECRNICAL NOTES NATIONAL ADVISORY COMMITTEE: FOR AERONAUTICS No. 715 - - _ - .- - i .- , - WIND-TUNNEL INVESTIGATION OF AN N.A.C.A. 23012 AIRFOIL , -+ r. .Jg WITH TWO ARRANGEMENTS OF A WIDE-CHORD SLOTTID FLAP By Thomas A. Harris Langley Memorial Aeronautical Laboratory Washington June
2、1939 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS . TECHNICAL NOTE NO. 715 WIND-TUNNEL INVESTIGATION OF AM N.A.C.A. 23012 AIRFOIL WITH TWO ARRANGEMENTS OF A WIDE-CHORD SLOTTED FLAP By Thomas A. Harris SU
3、MMARY An investigation has been made in the N.A.C.A. 7- by lo-foot wind tunnel of a large-chord N.A.C.A. 23012 airfoil with several arrangements of a 40-percent-chord slotted flap to determine the sectfon aerodynamic char- acteristics of the airfoil as affected by slot shape, flap location, and flap
4、 deflection. The flap positions for maximum lift, the polars for arrangements considered favorable for take-off and climb, and the complete set- tion aerodynamic characteristics for selected optimum arrangecnents were determined. A discussion is given of the relative merits of the various arrangemen
5、ts. A corn- parison is made of slotted flaps of different chords on the N.A.C.A. 23012 afrfoil. The best 40-percent-chord slotted flap is only slightly superior to the 25-percent-chord slotted flap from considerations of maximum lift coefffcient and-low drak for take-off and initial climb. . INTRODU
6、CTION The National Advisory Committee for Aeronautics has undertaken an extensive investigation of varfous wing- flap combinations to furnish information applicable to the aerodynamic and the structural design of high-lift devices for improving the safety and the performance of airplanes. A high-lif
7、t device capable of producing hgh . lfft with variable drag for landing and high lift with low drag for take-off and Initial climb is believed to be desirable. Other desirable aerodynamic features are: no increase in drag with the flap neutral; small change in pitching moment with flap deflection; l
8、ow forces required to operate the flap; and freedom from possible hazard due to icing, Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-2 N.A.C.A. Technical Note No. 715 It is planned in this investigation to test both simple and multiply slotted flap
9、s of different chords on airfoils of different profile. Some promising arrange- ments of medium-chord slotted flaps have been developed for the N,A.C.A. 23012 and 23021 airfoils. The aerody- namic data for these arrangements are reported in refer- ences 1 and 2. Further improvement from consideratio
10、ns of high lift coefficients and low drag at high and inter- mediate lift coefficients was obtained with the combina- tion of a modium-chord and a small-chord slotted flap (reference 3). Pressure-distribution data are also avail- able for the medium-chord slotted flap on the N.A.C.A. 23012 airfoil,
11、(See reference 4.) In the present report, the section aerodynamic char- acteristics are given for the N.A.C.A. 23012 airfoil equipped with a 40-percent-chord slotted flap in combina- tion with two slot shapes, MODELS Plain Airfoil The basic wing, or the plain airfoil, used in these tests was built t
12、o the N.A.C.A. 23012 profile and has a chord of 3 feet and a span of 7 feet; the ordinates for the section are given in table I. The model was built of solid laminated pine and had been previously used in the investigation of the medium-chord slotted flap reported in reference 1. The trailing-edge s
13、ection of this model is easily removable so that the model can be quickly al- tered for tests of dif-ferent flap arrangements. Slotted-Flap Arrangements . The slotted flap and the slot shapes were built of solld laminated beech. The slotshapes were bolted to the main airfoil in place of the solid tr
14、ailing edge, The flaps were mounted on special hinges that permittod considerable latitude in the location of the flaps with respect to the main airfoil. Flaps.- Only one flap shape was tested; it is de- , signated flap 1 (fig. 1 and table I). , This flap has a small nose radius and was designed to
15、give only a small . Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-N.A.C.A. Technical Note No. 716 3 . break inthe lower surface of the airfoil when undeflect- 0d. It also lends itself to use with a door to seal the break in the lower surface of the
16、 airfoil with the flap undeflected. mt shaoes.- The two slot shapes shown in figure 1 were used with the flap and are designated a and b. Slot ahape a was designed to give a minimum break in the lower surface of the wing and, consequently, to have the smaller effect on the drag wfth the flap neutral
17、. Slot shape b is simflar to slot shape h of reference 1, which gave the lowest drag at intermediate and high lift coefficients for take-off. The models were made to a tolerance of f0.015 inch. TPISTS 4 The models were so mounted in the closed test sec- tion of the N.A.C.A. 7- by 10.foot wind tunnel
18、 that they completely spanned the jet except for small clearances at each end. (See references 1 and 5.) The main airfoil was rigidly attached to the balance frame by torque tubes, Prrhich extended through the upper and the lower boundarias of the tunnel. The angle of attack of the model was sut fro
19、m outside the tunnel by rotating the torque tubes wfth a calibrated drive. Approximately two-dimensional flow is obtained with this type of installation and the section characteristics of the model under test can be determined. A dynamic,prossurs of 16.37 pounds per square foot was maintained for al
20、l the tests, which corresponds to a velocity of 80 miles per hour under standard atmospheric conditions and to an average test Reynolds Number of about 2,190,OOO. 3ecause of the turbulence in the wind tunnel, the effective Reynolds Number Re (reference 6) was approximately 3,500,OOO. Par all tests,
21、R, is based on the chord of the airfoil w%th the flap retracted and on a turbulence factor of 1.6 for the tunnel. Plain airfoil,- Tests were first made of the plain airfoil over the complete angle-of-attack range from -60 to the stall. Slotted flaosti- 31th each slotted-flap arrangement, tests were
22、made to determine the effect on minimum drag Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-. 4 N.A.C.A. Technical Note No. 715 . of the breaks in the wing lower surface at the slot en- trance with the flap retracted. Tests were also made to determi
23、ne the effect of the flap hinges with the flaps In their retracted positions. The tests of slotted flaps l-a and l-b consisted in force measurements with various flap positions and deflections to determine the optimum path of. the flap from considerations of low drag through- out the complete lift r
24、ange and of the highest maximum lift f-or each flap deflection. Data wore obtained for all tests throughout the angle-of-attack range from -60 to the stall at 100, increments of flap deflection from Oo to 50. No data were obtained above the stall because of the un- steady conditions of the model. Li
25、ft, drag, and pitching moments were measured for all positions of the flap over tho complete angle-of-attack range tested. RESULTS AND DISCUSSION Coefficients All test results are given in standard section non- dimensional coefficient form for the airfoil, corrected as explained in reference 1. wher
26、e 2 do m(a.cI)O* q* CWI and section lift coefficient (2 /w,) l section profile-drag coefficient (do/w,) g section pitching-moment coefficient about aero- dynamic center of plain wing (m(a.c.o /qcw=) is section lift, section profile drag. section pitching moment. dynamic pressure (l/m) l chord of. ba
27、sic airfoil wfth flap fu1l.y retracted, Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-N.A.C.A. Technical Note So. 715 5 . ; a0 is angle of attack for infinite aspect ratio. I . . 6ff flap d,eflection. Precisi.on* The accuracy of the various measure
28、ments in the tests is believed to be within the following limits:. u. - - - - - - - 9zO.l 0 =d - - - - - the points are plotted on the dial grams, The selected “optimum“ path referred to herein- after is shown by the broken line through the points and is a compromise. between aerodynamic and structu
29、ral consid- erations. The aerodynamic characteristics shown .in these figures are typical; complete data for other positions of the flap at the several flap doflectione are available up- on request. The erratic cd, for the 30 flap deflection of slotted flap l-b is typical of the results for this fla
30、p deflection. The lower values of cd, over the lift range from cl = 1.4 (a = -6) to 1.9 (a = -lo) have boisn disregarded in the selaction of the optimum path because the arrangement would probably be impracticable. In ad- dition, in a number of tests with ,larger gaps, two types of flow were encount
31、ered for this lift range; the other type gave a much higher cd,. The position for the flap at the 30 deflection was selected from consideration of maximum lift coefficient alone. Comourison of sclectod optimum arrangements.- In order to compare the drags-of the various flap arrangs- ments, onvelope
32、polars are giken in figure 10 for the Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-N.AC.A. Technical Note No. 716 9 slotted-flap arrangements of figures 8 and 9, As previ- ously mentioned, the low drag coefficients for the 30 flap deflections have
33、 been disregarded in-drawing the envelope polars for slotted flap l-b. Figure 10 shows slotted flap l-b to be superior to slotted flap La for take-off at any lift coefficient from 1.1 up to the maxf- .mum lift co0ffici0nt. Par lift coefficients less than 1.1, the plain wing haa. lower drag coefficie
34、nts than any of the arrangements with the flaps deflected. If a a002 *were used to seal ths break in the lower surface of the sing at the slot entrance, both of the slotted-flap ar- rangements would have approximately the same character- - - ._ istics as the plain iing f.or lift coefficients less th
35、an 1.1. A comparison of slatted flap l-a and l-b as lift- increasing devices is shown in figureli, -whersthe in- crements of maximum lift coefficient AC equal. For higher values of cl, the 40.percent-chord slotted flap is slightly superior for take-off. In addition, the 40-percent-chord slott0d flap
36、 for the extreme flap deflection gives higher values of It is probable howsvor ; - , I I I I 1 I 1 II I I I I 2 -12 I I t t I I III I I SF0 0 .2 .4 .6 .8 10 tf.2 I.4 I.4 Section lift coefficienf,q Figure 2.- Section aeroojmmic aea top and - hnt Kf = O”. * L I 4 07 . CA Provided by IHSNot for ResaleN
37、o reproduction or networking permitted without license from IHS-,-,-1.A.O.A. Taohnioallote Po. 7lS Pig. 4 Porosnt dng (a! 6,-l 8 6 4 a 0 Percent wing ohord 864a 0 P*romlt WiBg obad Co) 6, - zoo Rgur8 4.- Oontoum of flap location fez %u The 0.40 0, 8lotteb flap 1-a. 4 Provided by IHSNot for ResaleNo
38、reproduction or networking permitted without license from IHS-,-,-1.1.0.1. Too 6p10 8 Perokt 0 (b) oL-1.5; 6O“ 0 8 4 a 0 -Peroent dng chord Cc) q-a.0; bf-aoo 8 Perok l df-10 (b) q-1-s; 6flo” Puoent wl?lg ObJrd (0) q-a-0; 6+30 L-L! -! !U 8 6 4 Percent wing obxd (a) ol-a.6i 6f-20 rlgcre 7.- Oontourm o
39、f flap lcoatlon for s. The 0.4Ooc, dotted flap l-b. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-. N.A.C.A. Technical Note No. 715 Fig. 8 A 0 0 B IO 20 20 30 !EEE 5 I.5 I- 5535x5 .5 Illlrllrlll I I I I I I i figure 8.- Section aerodynamic cbw-oder
40、isfics of N.A.CA. 2.jWf2 airfoil with 0.4oc, slotted flop I-o. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-N.A.C.A. Technical Note No. 715 Fig. 9 - r:- . . - -.; . -1 .4 Secfim liff weffi Provided by IHSNot for ResaleNo reproduction or networking
41、 permitted without license from IHS-,-,-N.A.C,A. lCechnfca1 Note Ho. 715 c 4 . .a- Slotted flap Rlap deflection, 6f, deg. Figure ll.- Comparison of increment8 of section maximum lift coefficient for slotted flaps l-a and l-b when moved arid deflected alang the selected optimum paths. Provided by IHS
42、Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-f.t.8.A. Tsohnioal Note No. 715 Fig. 13 Flap chord, percent cw Figure 13.u Variation of increment of section maxkrum lift coefficient with flap chord. Slotted flaps on B.A.C.A. 23012 airfoil. - Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
